The author, an expert in nuclear proliferation, provides a detailed narrative of the hidden world of nuclear trafficking, mainly by exploring Abdul Qadeer Khan’s espionage and proliferation activities, how they were uncovered, and the significance of those events to the future of nonproliferation efforts. After describing Khan's role in establishing Pakistan's nuclear weapons complex, the author traces Khan's activities as he turned to exporting nuclear expertise and materials to other countries including Iraq, Iran, North Korea (DPRK) and Libya. The author reveals how complex, state-supported international networks of people, industries, and organizations bypass export regulations and avoid detection, allowing the spread of materials and expertise for developing nuclear weapons. North Korea’s efforts in the proliferation of nuclear technology and weapons delivery systems are also described. One interesting chapter explains how the Khan network was uncovered through the cooperative efforts of U.S, British, German, and Swiss intelligence agencies. However, prosecuting the guilty proved to be more difficult given the differences in the laws of the countries involved. The final chapters underscore the importance of a first line of defense against illicit trade in nuclear materials, noting that information and assistance from companies in the nuclear industry is necessary to stop nuclear proliferation. The author cites the successful cooperation between government and industry in Germany and Great Britain in identifying illicit procurement attempts as a model for the U.S. to follow.